Transparency effects in agrivoltaics lettuce cultivation using uniform/non-uniform semitransparent photovoltaic modules in controlled environments

Agrivoltaic systems offer a dual-use solution to land constraints by integrating food and energy production, yet the influence of light distribution characteristics—particularly uniformity—on crop performance remains poorly understood. This study investigates the physiological and yield responses of lettuce under two contrasting agrivoltaic lighting strategies while maintaining comparable transparency: (1) uniform illumination from cadmium telluride (CdTe) thin-film photovoltaic (PV) modules and (2) non-uniform illumination from bifacial crystalline silicon (c-Si) PV modules with alternating cell and glass regions. Experiments were conducted using CdTe modules at 40 %, 50 %, and 70 % transparency and bifacial c-Si modules at 44 % and 69 % transparency. Key parameters measured include photosynthetically active radiation (PAR), gas exchange metrics (photosynthesis rate, stomatal conductance, intercellular CO₂, transpiration), and morphological traits (plant height, leaf count, fresh weight). Results reveal that 69 % transparent c-Si modules not only preserved lettuce yield relative to open-field controls but achieved a 3.6 % enhancement. Conversely, CdTe modules of similar transparency caused a 6 % yield reduction, underscoring the importance of light non-uniformity in optimizing plant response. These findings demonstrate that spatial light heterogeneity – characteristic of c-Si systems – can enhance crop performance, presenting an opportunity for sustainable intensification. Scaling this technology across Canada’s lettuce-growing regions could generate 1,200 MW of solar power while boosting agricultural revenue by CAD $20 million annually, with an additional CAD $30 million from solar land leasing. This study supports the integration of non-uniform, semi-transparent PV modules as a viable pathway toward synergistic energy-agriculture systems for a sustainable future.